The subject matter discussed herein relates a base station congestion management system configured to determine as to whether or not congestion is occurring at a base station in a network in which data from a user terminal is distributed by a plurality of base stations to a plurality of gateway apparatuses.
Mobile service providers work on an important issue of improving a user quality of experience (QoE: Quality of Experience) for data communication service. One of primary causes to lower data communication service QoE includes occurrences of congestions at wireless access network (RAN: Radio Area Network) of mobile network. When congestion occurs at a RAN, control signals from a subscriber's terminal will not reach a mobile core network (EPC: Evolved Packet Core), which causes a phenomenon where the probability of the subscriber's terminal not being connected to the network increases, and a phenomenon where the throughput of the data communication by the subscriber's terminal will particularly deteriorate. These phenomena will prevent the subscriber from using desirable network services such as connecting with the Internet, thereby lowering QoE of services.
Conventionally, a technique for giving a feedback to a mobile network or to a subscriber's terminal concerning the occurrence of congestion at a RAN in mobile network so as to control and eliminate the cause of the congestion has been available. Once the cause of the congestion is eliminated the network connection probability for the subscriber's terminal and the data communication throughput will be improved, and service QoE will also improve.
As a background art of the present technical field, US patent publication No. 2014/0086052 (Patent document 1), US patent publication No. 2012/0257503 (Patent document 2), US patent publication No. 2013/0021933 (Patent document 3), US patent publication No. 2013/0170350 (Patent document 4), and ETS ITS 123 401 V12. 6.0, September, 2014 (Non-patent document 1) are available.
Patent document 1 discloses a charging system that dynamically changes the policy related to the traffic by a subscriber and the charging rule. The charging system as disclosed in Patent document 1 collects RAN traffic data, determines whether or not congestion is occurring at each base station of the RAN, and, based on the determination result of congestion, creates a list of subscriber terminals that are connected to the base station in a congested state. Also, the charging system as disclosed in Patent document 1 outputs to a PCRF an instruction to change the policy related to the traffic by a subscriber and the charging rule for the subscriber terminal included in the created list. By this, it becomes possible to reduce the traffic at the base station in a congested state, and resolve the congested state of the base station.
Patent document 2 discloses a congestion notification system configured to notify, when congestion is occurring at a base station, the subscriber terminal that is connected to the base station where the congestion is occurring. The congestion notification system according to Patent document 2 manages a list of subscribers that are connected to a base station for each base station in a manner similar to the charging system as disclosed in Patent document 1. Also, for determining whether or not congestion is occurring at a base station in the congestion notification system as disclosed in Patent document 2, bandwidth that is being used or usable bandwidth for a base station is used as a determining index, for example.
Patent document 3 discloses a RAN transfer apparatus for determining whether or not congestion is occurring at each base station in a RAN. The RAN transfer apparatus as disclosed in Patent document 3 monitors an S1-U, which includes an interface for transmitting and receiving data packets between a base station and an S-GW (Serving Gateway), which is one of EPC gateway apparatuses, and an S11, which includes an interface for transmitting and receiving control signals between an MME (Mobility Management Entity), which is one of EPC gateway apparatuses, and the S-GW. Also, the RAN transfer apparatus correlates the data packet that flows through the S1-U, the base station with which the subscriber terminal that transmits and receives the data packet is connected, and the subscriber of the subscriber terminal based on the contents of the control signals acquired from the S11. Also, the RAN transfer apparatus calculates, based on the correlation between the packet and the base station, the bandwidth that is being used at each base station, and compares the calculated bandwidth with a predetermined threshold so as to determine whether or not congestion is occurring at each base station.
Patent document 4 discloses a specific method for identifying a subscriber that corresponds with a data packet that is used in the determination method of whether or not congestion is occurring at a base station as disclosed in Patent document 3. To be more specific, a service quality management server monitors the contents of the control signals that are transmitted and received at the S11, correlates, based on the results of monitoring, a GTP tunnel ID (TEID (Tunnel Endpoint ID)), which includes a flow ID of the S1-U with an IMSI (International Mobile Subscriber Identify), which includes an ID of a mobile service subscriber, and saves the same. Also, the QoS system disclosed in Patent document 4 searches a corresponding subscriber ID for each piece of data packet by using TEID as a search key, and identifies the corresponding subscriber.
Non-patent document 1 discloses that in order to secure the performance and reliability of the S-GW an MME selects, when a subscriber terminal connects with the network, the S-GW with which of a base station will be connected for each subscriber. In other words, Non-patent document 1 discloses that a base station distributes traffic to one S-GW out of a plurality of S-GWs for each subscriber.    [Patent document 1] US patent publication No. 2014/0086052    [Patent document 2] US patent publication No. 2012/0257503    [Patent document 3] US patent publication No. 2013/0021933    [Patent document 4] US patent publication No. 2013/0170350    [Non-patent document 1] ETS ITS 123 401 V12. 6.0, September, 2014